Yo7 -- Your car is similar to mine Get the 1.12 or larger you won't regret it. FF has 1.18 also avlbl (their 1.06 is too weak.. forget about them)... even at 1.12 or 1.18 you'll wonder why not going a bit stiffer. Your big advantage is already having dbl adj shocks.. to fine tune your ride.

For the street (actually... highway) I run 15x8 minilite rims with BFG 255-60 and 275-60 (previously ran fronts 245-60.. but wanted a touch more ground clearance and bump absorption).. having a lowered suspension.. with my 1.24 TBs.... ride is just fine... stiff but not harsh or jaw breaking in any way. Adjustable red Konis.. full stiff front, ~1/2 stiff rear with 225# Flex-a-form mono-fiberglass leafs, 1.25" front sway bar, 1.0" rear sway bar. I also have 16" rims and short profile tires for track events.. street/hwy ok as well.

I've lowered the rear of the car as well, so there isn't as much of rake that introduces understeer with the different size tires...with the 275 rear tires there is only a slight rake, but then I typically have some items for cruising in trunk, etc... leveling off the height.

Hope this info is helpful to you.

PS: FF will make larger TBs upon request, such as 1.24 which is the max diameter to fit through the factory hex opening. The pro-TransAm e-bodies actually ran larger TBs.. around 1.44 diametar using different hex openings... so, the 1.24 TBs which I have (and a few other ppl I know) actually aren't that much stiff as many ppl think.